This invention relates to a floating magnetic head device advantageously used for writing or reading information signals on of rom a magnetic disc, also referred to herein as a hard disc. The invention also relates to a method for producing the floating magnetic head device.
The hard disc device, built into e.g., a computer for recording and reproducing the information, naturally includes a magnetic disc as an information recording medium and a magnetic head for recording and reproducing the information on or from the disc.
For avoiding damage to the magnetic head due to contact with the magnetic disc surface, a so-called contact start stop (CSS) floating magnetic head is in use as the magnetic head. The CSS type floating magnetic head is in surface contact with the magnetic disc surface during start and stop and is floated with an extremely small distance (flying height) from the magnetic disc surface by an air current generated on the disc surface during high-speed rotation of the disc.
The floating type magnetic head device includes a slider carrying a magnetic head, a gimbal spring in the form of a flexible plate spring secured to the slider, a suspension in the from of a plate spring having its one end secured to this gimbal spring and an arm mounted via a base plate to the other end of the suspension. The slider mounting end of the gimbal spring has a dimple providing a protuberance for limiting the floating distance of the slider carrying the magnetic head from the disc surface.
The slider is a substrate formed e.g., of Al.sub.2 O.sub.3 --TiC and is usually prepared by machining using a grindstone. The slider is made up of an air inlet groove for causing the magnetic disc to be floated with a small flying height from the magnetic disc in a stabilized floating state, a pair of slide rails formed on both sides of the air inlet groove and a magnetic head element fabricated by a vacuum thin-film forming technique on the slide rails on an end face thereof directed towards the air inlet end.
Each slide rail has an air lubricating surface, an air inlet end of which has a small taper which is a moderately inclined surface with a gradient of not more than 1.degree.. The slider is floated under an air pressure generated on each air lubricating surface. The tapered portion is responsible to a greater extent for the generation of the air pressure on the air lubricating surface.
The magnetic head has a lower-layer core on the substrate, a conductor coil and an upper layer core formed on the lower layer core via an insulating film. The upper layer core and the lower layer core are magnetically coupled to each other via a back gap and a magnetic gap, with the conductor coil in-between, for constituting a magnetic circuit.
With the above-described floating magnetic head, the slider is contacted with the magnetic disc surface during start and stop and is slid on the magnetic disc surface immediately after start and immediately after stop. Thus the floating magnetic head suffers from the problem of low CCS durability. There is also a problem that powder debris generated due to sliding contact between the two surfaces becomes affixed to the slider surface to cause premature deterioration of the floating performance of the slider.
Thus it may be envisaged to use an upper layer of hard carbon typified by diamond-shaped carbon on the slider surface. The diamond-shaped carbon can be formed into a film at lower temperatures. In addition, the diamond-shaped carbon exhibits self-lubricating properties when in the state of a thin film and has a low frictional coefficient and high hardness on being formed into a film, so that it is superior in abrasion resistance. Thus, by forming the upper layer of hard carbon, it becomes possible to prevent abrasion which otherwise tends to be produced between the slider surface and the magnetic disc surface.
Recently, a demand has been raised towards high density recording on the hard disc. For meeting this demand, it is necessary to reduce tie flying height to as small a value as possible. For suppressing the spacing loss, the upper layer needs to be of an extremely reduced thickness, while the upper layer needs to exhibit sufficient adhesion with respect to the slider. However, the upper layer formed of hard carbon, especially diamond-shaped carbon, has a higher internal stress and poor adhesion with respect to the slider. On the other hand, the smaller the thickness of the upper layer, the more significant is the lowering of adhesion thereof with respect to the slider.